Lathe



W. BUTTRUM.

LATHE.

APPLICATION HLEDDEC-4. 1920.

1,49 ,54 Patented Aug. 22, 1922.v

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LATHE.

APPLICATION man 050.4. 1920.

Patented Aug. 22, 1922.

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' LATHE.

APPLICATION FILED 950.4. 1920 Patented Aug. 22, 1922.

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' W. BUTTRUM.

LATHE.

APPLICATION FILED DEC. 4. 1920.

1,426,546,. Patented u .22,1922.

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v unites stares WILLIAM Burrnumor aorLIN, MISSOURI.

LATHE.

V Specification of Letters Patent. Pgrtgntd Aug, 22', 1922 Applicationfiled December 4, 1920. Serial No. 428,853.

To all whom it may concern:

Be it known that I, VVILLIAM BUTTRUM, a citizen of the United States,and a resident of Joplin, in the county of Jasper and State of Missouri,have invented certain new and useful Improvements in Lathes, of whichthe following is a specification.

The present invention relates in general to lathes, and moreparticularly to an attachment for lathes especially adapted tofacilitate the carrying out of various thread cutting operations. v

The object of the inventionis to provide an attachment for lathesof thischaracter which adapts the conventional or standard lathe to carry outthe accurate cutting of threads of various pitches of standard orspecial design, with a minimum expenditure of time and of skill andwithout impairing the original capacities oradvantages of the lathe;which is of 'simpleand durable construction, reliable in operation, andeasy and inexpensive to manufacture, and which in general endows thelathe with new features, advantages and capacities without deo tractingfrom those originally existent there- Other objects and advantages ofthe invention reside in certain novel features of construction,combination and arrangement of parts which will be hereinafter morefully described and particularly pointed out in the appended claims,reference being had to the accompanying drawings forming part of thisspecification, and in which:

' Figure 1 is a side elevational view, Show ing the invention assembledupon a conventional lathe;

Figure 2 is a detail view in side elevation of. the invention, partsbeing shown in dotted lines for the sake of illustration;

Figure 3 is a transverse vertical sectional view on line 3 3 of Figure2, looking in the directions of the arrows; c

Figure dis a transverse vertical sectional view on line 4-4 of Figure 2,looking in the direction of the arrow;

Figure 5 is a detail perspectiveview ot the invention and the associatedportions of the lathe; v

Figure 6 is a fragmentary rear elevational view of amodified form;

Figure 7 is a, fragmentary detail view in side elevation of the type ofscrew; used in the modified form.

Referring to the drawings, it will be seen thatthe inventioncontemplates a lathe or any standard or conventional construction whichincludes as usual a suitable base such as legs 10 upon which a bed llissupported.

The bed 11 includes ways or shears 12 which slidably receive a carriage13 including a saddle 14 and an apron 15. A cross slide 16 1s arrangeduponi the saddle and carries a tool post 17. The head stockj18 isarranged at one end of the lathe and in itis j ournaled a lathe spindle,19 adapted to be driven directly or by suitable gearing from the conepulley 20. Change gears 21 are provided, and drive a leadscrewf22, whichis adapted to cooperate with the mechanism of the apron of the carriagefor feeding "the carriage longitudinally and for operating the crossfeed'when desired'. A- feed rod 23 is also provided, and is adapted tobe driven from the spindle ofthe lathe'to feed the carriagelongitudinally through the coop eration therewith of theconventional'mecb anism of the" lathe apron andrack 24: secured to thebed of the lathe.

An extension 30 for the vcarriage is provided and is secured tothecarriage by means of screws 31 and nut 32 and a strap 33 and boltsand nuts 34. The extension 30 includes a'saddle portion 35 adapted-tocooperate with the ways or shears or the lathe and an apron portion 36.y

A bearing bracket is adjustably arranged on the ways or shears ofthebedof the lathe, and'is adapted to be secured in adjusted position bymeans of a bowed clamp plate 38 and clampnuts and bolts 39. The bracketincludes a depending bearingportion 40.

An auxiliary leadjscrew 45 of tubular form is arranged upon the leadscrew 22 and is splined thereto so as to be constrained to partake ofthe rotary motion of the'lathe screw while free to partake oi relative1011+ gitudinal motion with respect thereto. For this purpose the leadscrew is a key way 22* throughout its entire length with which isadapted to'cooperatefeathered keys or the like 46 'carried'by theauxiliary lead screwand slidably received in the key-way of the leadscrew 22. The periphrovided with cry of the auxiliary lead screw 45 isprovided with screw threads 45 'oi a pitch and character correspondingto the pitch of -"the threadsto be cut, The extension SO-te the vcarriage is provided on the rear face O'li its apron with spaced plates4t? having provided therein ways 4-8 which slidably receive flanges 49carried by sections 50 and 51 of a split clamp nut adapted to engage thethreads of the auxiliary screw. Means is provided for moving the clampnut sections into and out of engagement with the auxiliary screw andincludes a cam disk 52 having cam grooves 52" and 52 therein adapted tocoact respectively with pins 53 and 53 carried upon the sections 50 and51., respectively of the clamp nut. he cam disk is controlled by ahandle carried at the outer end of a shaft 54 to the inner end of whichthe cam disk is secured.

At one end, the auxiliary screw 45 is enlarged and provided with ashoulder 55 which is adapted to abut the bearing portion 40 of thebracket and beyond the, shoulder 55 the auxiliary screw is formed with are duced extension 56 received in the bearing of the bearing portion 40and extending therebeyond. The portion extending beyond the bearing 40is provided with screw threads with which a nut 57 and thrust collar 58engage. The thrust collar 58 coopcrates with the opposite side of thebearing portion from the shoulder 55 and maintains the auxiliary screwagainst longitudinal mo tion with respect to the bed of the lathe. Ateach end of the auxiliary screw and between the auxiliary screw and thelead screw are carrier rings 59 to properly support the auxiliary screwor the lead screw.

An adjustable stop pin 60 projects laterally from one side of thebearingbracket and is adapted to engage the carriage to limit the movementthereof toward. the bearing bracket.

In practice an auxiliary screw is selected which has on its peripherythreads of the character and pitch corresponding to the threads to becut and this auxiliary screw is then assembled on the lead screw of thelathe, as shown in Figure 2. The bearing bracket'is then adjusted to theposition on the bed of the lathe which will give the carriage a range ofaction and location which is best adapted to carry out the operationsupon the peculiar work in the latheand the bearing bracket is thenclamped in this position by means of the clamp nut and bolts 39 andclamping plate 38. The tool etc., of the lathe is manipulated in theusual manner but the longitudinal feed of the carriage is controlled bythe auxiliary lead screw. The utility, of the adjustment may perhaps bebest understood by a consideration of its action with respect to acertain form of lathe rather widely used. This type of lathe is equippedwith a standard le-thread lead screw and in cutting an S-thread, thegear ratio is set at 4896 or two to one, that is for every turn of thelathe screw there is two turns at the'cutter. Consequently, the cutterwill catch on any position of the lead screw and the four positions ofthe lead screw is represented by every other thread cut. Now however incutting a 'Y-thread with the same lead screw the gear ratio is changedfrom 48-96 to 48--84 and only one position of the d-thread on the leadscrew will catch, for now every thread on the lead screw corresponds to11 threads at the cutting edge. To cut the 'f-thread, it is there forenecessary to catch the tool in every fourth position. This requires astopping of the lathe and the measuring back of an equal number ofinches for the correct position or else the leaving of the machine runand dropping back one inch beyond the beginning of the thread to waitingof the rotation of the lead screw for the correct position of the leadscrew to be presented so that it will catch and then following it up tothe beginning to be sure you have the correct position. If it is in thewrong position the same operation is repeated making it a-cut and-trymethod.

In a cutting of a T-thread with my attachment, the gear ratio is notchanged, but left the same as an 8-thread. The lead screw is changedfrom a four thread to a thread screw and a screw bears the same ratio toa 'Z-thread that a l-thread screw bears to an 8-thread. This makes thecut of the 7-thread screw as simple as that of an S-thread.

in the above illustration reference is made to a T-thread entirely butthe same theory is applicable to and is carried out by the presentinvention with respect to a 5, 9 or any odd thread required by simplyinserting the attachment of the proper pitch. For example, a 5-threadrequires a pitch in the attachment, a Q-thread a t} pitch, etc.

In the modification of my invention shown in Figures 6 and 7, theauxiliary screw is shown as having its exterior provided with two setsof screw threads, designated at 61 and 62 of different pitch andcorresponding to I different character of threads to be cut. Theextension of the lathe apron, designated at 30 is provided with two setsof split clamp nuts, desig nated at 63 and 64 of a constructionidentical with the single clamp nut of the preferred form of invention.It is to be understood that the clamp nut 63 is adapted and onlycooperates with the section of the lead screw 62 and that the clamp nut64: corresponds to and is adapted to cooperate only wi h the section ofthe lathe screw bearing the lead screw 61.

The action and operation of the m0dification is substantially the sameas that ofthe preferred form first described except that in thisinstance two varieties of thread may be cut from the same auxiliaryscrew.

In either embodiment of the invention it is to be understood that thereis provided a sufficient variety of auxiliary screws to take care of thevarious thread cutting operations, although by the provision of threadsof different pitches on the same screw a'wide range of selection may behad from a compartively few auxiliary screws. In this latter event it isnot necessary to change the auxiliary screws to meet the exigencies ofeach particular thread cutting operation.

I claim:

1. A thread cutting attachment for lathes including a bed, a carriageand a lead screw and comprising an extension, means for securing saidextension to the carriage, a bracket having a depending portion providedwith a bearing, means for adjustably securing said bracket to the bed,an auxiliary screw having its exterior provided with threads of a pitchvcorresponding to the threads to be cut and adapted to be arranged uponand constrained to rotate with the lead screw, said auxiliary screwhaving a shoulder abutting the bearing of the bracket and a reducedextension beyond the shoulder rotatably received in the bearing, meansfor maintaining the auxiliary screw in proper relation with respect'to'the bearing including a thrust collar secured to the auxiliary screwand engaging the bearing, and a nut for securing the thrust collar inposition, and a split nut carried by the extension and engageable withthe auxiliary screw.

2. A thread cutting attachment for lathes including a bed, a carriageand a lead screw and comprising an extension, a bracket having adepending portion provided with a bearing, an auxiliary screw having itsexterior provided with threads of a pitch corresponding to the threadsto be cut and adapted to be arranged upon and con strained to rotatewith the lead screw, said auxiliary screw having a shoulder abutting thebearing of the bracket and a reduced extension beyond the shoulderrotatably received in the bearing, and means for maintaining theauxiliary screw in proper relation with respect to the bearing includinga thrust collar secured to the auxiliary screw and engaging the bearing,and a nut for se curing the thrust collar in position, and a split nutcarried by the extension and 'engageable with the auxiliary screw.

3. A thread cutting attachment for lathes including a bed, a carriageand a lead screw and comprising an extension, a bracket having adepending portion provided with a bearing, an auxiliary screw having itsexterior provided with threads of a pitch corresponding to the threadsto be cut and adapted to be arranged upon and con strained to rotatewith the lead screw, said auxiliary screw having a shoulderabutting thebearing of the bracket and a reduced extension beyond the shoulder rotatablyreceived in thehearing, and means for malntaining the auxiliaryscrew in proper relathreads of a pitch correspondingto the threads to becut. and a split nut carried by the extension and engageable with theauxiliary screw. I

5. A. thread cutting attachment for lathes including a bed, a carriageand a lead screw and comprising an extension adapted, to be directly andrigidly secured to the carriage, a bracket adapted to be adjustablysecured to the bed and provided with a bearing, an auxiliary screw.adapted to be arranged upon and constrained to rotate with the lead for..lathes I i screw and to be rotatably journaled in the bearing of thebracket and having its ex terior provided with threads of av pitchcorresponding to the threads to be cut, and a split nut carried by theextension andengageable with the auxiliary'screw,

6. A thread-cutting attachment forlathes including a lead screw and acarriage and comprising an auxiliary screw adapted to be arranged uponand constrained to rotate with the lead screw and having its exteriorprovided with threads of a pitch corresponding to the threads to be cut,and means directly and rigidly connected with the carriage and operableto be selectively engageable with the auxiliary screw, all as and forthepurpose set forth' 7. A thread cuttlng attachment for lathesincluding a carriage and .a lead screw having a spline, and comprisingan extension adapted to be secured to the carriage, a hollow auxiliaryscrew having its exterior provided with threads oi a pitch correspondingto the threads to-be cutand adapted tobe arranged upon. the lead screw,a feathered key cooperable with the spline of the lead of a pitchcorresponding to the threads to be cutand a manually operable split nutdirectly and rigidly connected to the carriage and operable so as to beengageable'wit-h the auxiliary screw.

screw to constrain the auxiliaryscrew to ro 9. A threadcuttingattachment for lathes including a carriage and a lead screw andcomprising an extension adapted to be rigidly and directly secured tothe carriage, 2L

5 bracket having a hearing adapted to be secured t0 the bed, a, hollowauxiliary screw adapted to be arranged upon and constrained to berotated with the lead screw screw whereby said cutting motion isimparted to the carriage.

WILLIAM BUTTRUM.

